Ammonium silicates



United States Patent i 3,346,334 AMMONIUM SILICATES Helmut Hans WilhelmWeldes, Havertown, Pa., and

Mahlon Robert Derolf, Blackwood, N.J.,;assignors to Philadelphia QuartzCompany, Philadelphia, Pa., a corporation of Pennsylvania No Drawing.Filed Dec. 16, 1963, Ser'. No. 330,575

6 Claims. ((11. 23-110) This invention generally relates to a newprocesswhich results in the production of ammonium silicate solutionswhich have not been known before. More particularly this inventionrelates to the production of novel ammonium silicates having a loweralkali metal ion content and a smaller particle size than has ever beenknown. There has long been a demand for a solution of a substantiallyalkali metal-free ammonium silicate having high ratios of SiO and (NH Owith respect to alkali metal oxide and a low silica micelle diameter.While there have been a number of attempts to prepare such solutions,none has been successful in a practical sense.

Efforts to prepare ammonium silicates directly have failed.Ammoniumhydroxide is not a strong enough alkali to dissolve silica geleven under conditions of elevated temperature and pressure.

Double ammonium and alkali metal silicates lack the properties soughtfrom ammonium silicate solutions.

In the prior art, silica sols stabilized with ammonia have been known.Usually the sol has been prepared by one of the usual processes and thenhas been stabilized by the addition of ammonia as an alkalinestabilizing agent. In other cases, silica gel has been peptized bytreating the gel under various conditions with ammonium hydroxide.

In some cases, the sol has been prepared by removing the alkali metalwith ion exchange resins and then stabilizing by the addition ofammonia. The preparation of such a stabilized sol has also been carriedout by treating a sodium silicate solution with an ion exchange resin inthe ammonia form. All of these processes have resulted in products withlow ratios of silica to alkali metal oxide and/or ammonium oxide toalkali metal oxide although they may be substantially free of alkalimetal ions. The silica particles are in the colloidal range and have alow viscosity even at high concentrations because of the density of thesilica particles. In other words, these prior art stabilized sols, whichhave in some cases been called ammonium silicates, are more accuratelydescribed as stabilized silica sols.

The records of many years show the desire for ammonium silicates(substantially free of alkali metal ions) for the treatment of clays,for humidity control, for cements, coatings and adhesives. Such cements,coatings and adhesives should have higher resistance to breakdown byheat Or weather. It is the rimary object of this invention to producesuch ammonium silicates. Various other objects and advantages will beapparent after reading the following detailed general description andexamples.

In this application the ratios refered to are mole ratios and theparticle sizes are average particle sizes unless otherwise specified.

THE PRESENT INVENTION Considered from one aspect the present inventioninvolves a method which comprises:

(a) Introducing an aqueous solution of an alkali metal silicate into areaction zone,

(b) Also introducing into said reaction zone a material selected fromthe group consisting of ammonia and ammonium hydroxide and bringing saidmaterial into admixture with said alkali metal silcate to there-3,346,334 Patented Oct. 10, 1967 thereby produce a double silicatesolution of an alkali metal and ammonia,

(c) Contacting said double silicate solution with a cation exchangeresin that is 50% to 100% saturated with ammonia,

(d) Recovering an ammonium silicate solution that has a ratio of SiO toalkali metal oxide of at least 25; an (NH O to alkali metal oxide ratiothat is at least 8, and that has silica micelles that are on the averagenot larger than about 3 m in diameter.

As our alkali metal silicate solution we prefer to use sodium orpotassium silicate solutions having the highest possible ratio of silicato alkali metal oxide since this reduces the amount of alkali metalwhich has to be removed during subsequent processing. As a practicalmatter, the ratio of Si0 to metal oxide may vary from about 2 to about4. At the lower ratios, the efiect on the final alkali metal content ofammonia added to the silicate solution is much less noticeable becauseof the relatively higher concentrations of alkali metal and the longtime required to remve the last residues of alkali metal oxide.

Also, as a practical matter, we would not expect to use a concentrationof SiO which would result in final products having a SiO content lowerthan about 1% by weight. We may use silicate solutions which will resultin final products having up to about 12% by weight SiO but if nearlycomplete removal of Na O is required we find that final SiOconcentrations of about 6 or 7% SiO are preferred.

With regard to the ammonia or ammonium hydroxide, diluted commercialammonia (29% NH is preferred because of its availability.

The ammonia or ammonium hydroxide is usually added to the point ofinstability, and more particularly the amount is chosen so that theratio of SiO to (NH O is within the range of about 2 to about 6, andpreferably below about 4. If the amount of ammonia or ammonium hydroxideis increased beyond the amount indicated by this range the volatility ofthe ammonia in both the initial double silicate solutions and the finalammonium silicate porduct also increases and the actual loss of NH aswell as the odor becomes a problem. Too high proportions of ammonia tendto precipitate silica or an ammonium silicate complex. It is preferableto avoid such precipitation.

The double silicate solution prepared according to the above proceduremay contain from about 1 to 12% by weight of SiO a SiO to alkali metaloxide ratio of between about 2 and 4; and a (NHQ O to alkali metal oxideratio of between about 0.4 and 2.5.

The above double silicate solution may be slurred or otherwise treatedconcurrently or counter-currently with a cation exchange resin loadedwith ammonia. A num ber of cation exchangers are suitable for thepresent process and by way of example the cation exchangers set forth inU.S.P. 2,671,056 are suitable.

The cation exchange resin we have found most suitable is a highlycross-linked nuclear sulfonic acid type cation exchanger, but otherknown cation exchangers may also be used. A typically suitable resin isshown in the examples below. In order to use this base exchange resin Wetreat it with the required amount of ammonia in order to prevent undueloss of ammonia from the double Silieate solution while removing thealkali metal ion therefrom. In general, we prefer to use resin saturatedwith ammonia; that is, with 100% loading, but lesser loading such as90%, or even 50% may be used. Resins with lower ammonia loading willremove ammonia along with the alkali metal ion from the double silicatesolution and thus we prefer to use the saturated resins or those havinga -100% ammonia loading.

The contact time of the ammonia loaded resin with the double silicatesolution was usually about six minutes in our experiments. Longer orshorter times (e.g. 4-30 minutes) may be used, but as a practical matterWe have found that the content of alkali metal ion is reduced to areasonable low level in about six minutes. While this low level would befurther reduced by longer exposure, the rate of removal would of coursebe less.

It is preferred that the ratio of grams of double silicate solution toml. of cation exchange resin fall within the range of about .40 gr./ml.to about 2.5 gr./ml. With higher proportions of loaded resin therequired contact time can be shorter but our experience has been thatvery good results can be obtained in the six minutes on which we havestandardized when using the proportion of Gil to alkali metal oxidestabilized silica sols in an amount calculated to give compositionsapproximately the same as the ammonium silicate solutions formed by themethod of our invention. Light scattering data shows that not only arethe particle sizes much larger in such stabilized silica sols but inaddition the particle sizes are increased by the addition of theammonia. More specifically, our ammonium silicate solutions have averageparticles in sizes not larger than about 13 millimicrons whereas thestabilized sols have particle sizes not smaller than about 7 rm (and notsmaller than about 10 m after the addition of ammonia).

EXAMPLES IN GENERAL resin shown in our examples. When a ratio of resinto The following eXampleS are illustrative of some P silicate l iexceeds h i di d b h above ferred embodiments of the present invention.It should be range it has been Observed h ll f h d bl ili understoodthat these examples are not intended to limit solutions may becomeabsorbed by the resin, which rethe invention and that Obvious Changes ybe made by Sults i h hd mass those skilled in the art without changingthe essential Aft treatment of h d bl ili i h h resin characteristicsand the basic concept of the invention. in the manner set forth above,the resin and product solu- The Parts and Percentages are y Weight, thetemperature tion are separated. The resin may then be regenerated isroom temperature and the Pressure is atmospheric, d teusetl lessotherwise indicated.

The ammonium silicate solution which is the product In the followingeXampleS the ammonia Solution of our invention has a ratio of SiO toalkali metal oxide of 5 ferred t0 t5 the Standard Commercial ammoniaSolution at least about and up to 150 or higher. We prefer prod-Containing 29% s- The ammonium Sulfate used is ucts having a ratio of atleast 50. The mole ratio of amagent grade- LUdOX SM and LhdOX HS arealkali Stabimonium oxide to alkali oxide is greater than 8 and rangeshZed Silica 3013 Solid y E du Pent de Nemours & up to about 40 or more.The mole ratio of SiO to am- LudOX SM has a Particle SiZe of about 7Ill/L, and LudOX monium oxide can be lower than the mole ratio of silica30 HS has a Particle SiZe of about 15 is the to Na O in the startingsadium silicate solution and pretrademark of the Philadelphia QuartZ P yfor a ferably ranges from about 2 to 8. The silica concentra- SodiumSilicate Solution having a 2 t0 z ratio by tion in the final product maybe as high as 12% by weight Weight of t0 1 and which Contains 253% yWeight of SiO although we prefer to prepare solutions at about zis thetrademark 0f the Philadelphi'a Quartz 6% $10 as we h fo d h thgse aremore dil 35 Company that designates a sodium silicate solutionhavprepared with low alkali metal contents. The silica micelihg 2 t0Neat) ratio y Weight of 211 and Which has 165 are on th average notlonger h about 3 illi ia silica content of 29.4 weight percent. Theparticle sizes cr i di m t hi h i b i ll l h thoss in these solublesilicate solutions are not more than about available from commercialsilica sols, including silica sols 1 which are stabilized by ammonia).40 Example 1 hea ti rig 11 3 it ii th liiffe ".iiiiil iiii 50.? ti i "EA grams 78-35 Swim Sum a solution without loss ammonia A 2 r fwasdrluted with 805 grams of distilled water wzthout the crease th f thl1 ea addition of ammonza. This SOllltlOlJ contalned 1.60%

S e 5126 e 811% es of slllca Partlcles Na O, 6.00% SiO and had a moleratio of SiO /Na O present In the solut1on. of 3 gfiig sg g g sgsi ssiig ;;f g wl'th A 100% ammonia loaded Amberlite IR-124 resin was moniumsilicate Produced in acordanc i ifi h prepared by treating 500 ml. ofthe catlon exchange resin to d h f2 46 e 15 mven' 1n the hydrogen formwith a solution of 280 g. of am- 1 n a 1O 2/(CN H4)2O and 57% momumsulfate in 500 g. of water. This was twice the y Welght 0f 2 1Slhfihltely h e Wlth methanol and 50 stoichiometric amount of ammoniumion needed to conf tlmes more mlselble Wlth other Water vert all of theexchange capacity of the resin. The treated clble Ofgehle Solvents (Suchas methanol, han l, isO- resin was washed free of sulfate ions and 20grams of propyl alcohol, acetone, dioxane, tetrahydrofuran) than theabove dilute sodium silicate solution were treated is a sodium silicatehaving the same ratio and concentrawith 15, 20 and 25 ml. of the ammonialoaded resin. The tion. Our ammonium silicate solutions are, therefore,compositions of the resulting ammonium silicate solumore applicable inliquid detergents, for instance. tions are shown in the following table:

Mole Ratios i i iiiiii l-1 3m) 32318 Sign Sim/(Name sioi naio (NHmO/Na Op p p It should be noted that the amount of alkali metal ion Example 2in the Product of this invention is less than would be The advantage oftreating a double silicate solution Present 1t exhetly the Same exchangeProcess Was carried containing an alkali metal and ammonia with 'a 100%out with sodium silicate rather than the double silicate ammonia l d dti i resin, as we h di by WhlCh we use. our invention, is illustrated bythe following example.

The process and products of this invention are definite- A doublesilicate solution A was prepared by' diluting ly quite different fromany similar prior art process or 250 grams of S35 with 500 grams ofwater and then product, as will be evident from the examples whichmixing with a solution of 29.9 grams of aqueous amfollow. monia in 275.1grams of water. These components were In order to illustrate onedifference, we added ammonia mixed with vigorous stirring and formed aslightly hazy,

stable solution containing 1.60% Na O, 1.25% (NHQ O, 6.00% SiO Thesolution had mole ratios as shown in the table below, and 20 gramportions of A were treated with increasing amounts of the 100% loadedresin, as shown, for six minutes.

6 creased about millimicrons by the addition of ammonia. The particlesize of Ludox HS was found to have increased from to about 19.5 m by theaddition of ammonia.

5 (For this test we used a Lumetron colorimeter sold by g Mole RatiosAmount of N820 (NH4)20 S10 Resin (percent) (percent) (percent)Sl02/(NH4)ZO moi/N620 (NHflzO/NaaO A alone 4. 16 3. 87 0. 93 1. 60 1. 256. 00 ml 3. 64 25. 3 6. 94 0. 23 1. 34 5. 62 ml 3. 64 34. 1 9. 37 0.l7 1. 34 5. 62 ml 3. 88 36. 3 9. 36 0. 16 1. 25 5. 62

A double silicate solution B was also prepared by adding a solution of59.8 grams of aqueous ammonia in 245.2 grams of water to 250 grams of S-diluted with 500 grams of water. This also formed a slightly hazy,stable 20 Photovolt Corporation. The scale setting 100 was standardizedwith a 1.25% silica sol of known particle dimension (Ludox SM) usingthroughout the test the filter for a wavelength of 365 m and a mercuryvapor lamp.)

Example 3 In this example the double silicate was treated with a 50%ammonia loaded resin to demonstrate the importance of using a nearlysaturated resin. The double silicate was prepared by diluting 250 gramsof S35 with 500 grams Mole Ratios Amount of Resin N220 (NHmO S102(Percent) (Percent) (Percent) SiO2/(NH4)1O sioz/Nazo (NH4)gO/N3.z0

It is evident that the best result was obtained in the last series using30 ml. of 100% ammonia loaded resin with 20 grams of double silicatesolution B. This test was repeated on a larger scale with the sameresults. The ammonium silicate solutions obtained were stable for atleast several weeks. Since they smell strongly of ammonia they should bekept in closed containers to prevent loss of NH The solutions areslightly hazy and water thin.

In order to make a comparison between the particle size of ammoniumsilicates produced in accordance with this invention and alkalistabilized silica sols that have had ammonia added to them, severaltests were carried out. 100 grams of Ludox SM having particles of 7 m insize was treated with 11.4 grams of aqueous ammonia. Also, 100 grams ofLudox HS having a particle size of 15 m were treated with 22.8 grams ofaqueous ammonia. Both mixtures were diluted to 500 grams with water andformed stable mixtures having the composition shown below:

of water and adding 22.2 grams of aqueous ammonia diluted with 282.8grams of water. The slightly hazy, stable solution obtained had aconcentration of 1.60% Na O, 0.93 (NH O and 6.00% Si0 with a mole ratioof SiO /Na O of 3.87, SiO /(NH O of 5.56 and (NH O/Na O of 0.70. gramsof this double silicate solution were treated with 45 ml. of a 50%ammonia loaded resin for six minutes. The loaded resin was prepared aspreviously described. A stable solution was obtained having 0.11% of NaO, 0.24% of (NH O and 5.86% of SiO with a mole ratio of SiO /Na O of55.1, SiO /(NH O of 20.76 and (NH O/Na O of 2.66.

It contained almost as much Na O as ammonia and it was evident that someammonia, as well as the sodium, was removed by the ion exchange resin.

Example 4 i A further series of tests was carried out using D sodiumsilicate at 6% Si0 concentration. A starting solution a Mole Ratios N O(NH) O o 811' S a 42 2 ma oume (Perc ent) (Percent) (Percent)SiO2/(NH4)2O SiOz/NazO (NH4)20/N8z0 Each of these solutions was given astandard light was prepared with 40.8 grams of D diluted with 159.2

scattering test and compared with the original Ludox HS and Ludox SM. Itwas found that the ammonium silicate solution had particle sizes of 2 to3 millimicrons which was well below the particle size of Ludox SM (7 mwithout ammonia. The particle size of Ludox SM is in- 20 grams ofsolution h mixtures are SiO (percent) Example 6 M (percent)0858715371422 8065 0321882178645 4228 LLL0 QL2LLLL22 2 22 L lid becauseof the absorption of the solution by 80 71 57 D49 0-342033%22032T2103222w 3 0 0 0 0Q3 0 0O Q0 3 0 0 0 0 0 semi-so the resin.

(N114) zO/ MO 8 9 39086438609977815 OA 45 3 A Q7 7 &&&QOWLO ZL 1111three starting solutions h varying amounts of following table:

Mole Ratios Slot/ 520 containing a before treatment with the on ofsodium (i.e. the D sodium hat the addition of ammonia to Amount of Resinmonia. 20 gram portions of these were treated for six minutes witammonia saturated resin as shown in the Starting Solution a Even withthe sodium silicate solutions relatively high proporti silicates) it isevident t the sodium silicate solution 2 h &m.n m o mU .n2sd H mm m m N0 6.1 d(\ s w m m w 310 O a 0 .1 6 OS e s mw 6 n7d u mw m s w m u m fim9 m -D3 23 .1 0 11 .n 5 corn 4 mummam S n (0 .l a y 2 h m Z 0 a ldMW e m2 u. a yo. 0 mwa a t mbz X OO 0 R W S 2.1 a as m n S m n O O I a M 2m Wm3r 0 3 f 2 n a .m t a0 It i n e C n 0 c e ammonia loaded resin helpsmaintain SiO and increases the proportion of ammonia Example 5 cries oftests the Si0 concentration SiO S102 (percent) ble. While the re- (N 02(percent) silicate starting solution 11 Na O, 4.18% (Ni-I9 0, le ratios.When 20 gram lutions were treated with or more of SiO;; may

N320 (percent) 051 7 4 265 swam M 3 0 0 20 00 00 Example 7 S10 (percent)A somewhat similar double was prepared having 2.67% 10.0% SiO and thesame mo portions of these two starting so the saturated ammonia sultswere as shown in the following ta they show that solutions with 10% betreated in this way.

Mole Ratios siozlNaio ratio of 2.07.

7 7 802 800834 3 04 4om7 3 & 12 33456 O (NH4)20 (percent) -In thisexample we have demonstrated the usefulness SiO2/(NH4) 20 N820 (percent)um silicate. 68.0 grams of D Amount of Resin lution e was prepared with68.0 grams of D, 122.6 grams of water and 9.4 grams of aqueous ammonia.

using the same D sodi Starting solution d was prepared using and 132.0grams of water.

Starting double silicate so Starting double silicate solution 3 wasprepared with ammonia. As before, 20 grams of these starting solutionswere was raised to 10% of aqueous (NH4) nO/NMO Mole Ratios ea aa mmAmount of Resin treated for six minutes with the saturated ammonia resinas shown in the following table:

Starting Solution (1.

Again, the higher ammonia content in the double siliof our ammoniumsilicate solutions for deflocculating lica and increased the residualamclay. A mixture of 315.9 grams of 8-35, 941.8 grams licate solution.However, of water and 75.6 grams of aqueous ammonia was prehan in thehigher pared and treated for six minutes wtih 2,000 ml. of the cateprotected the si monia in the final ammonium si the sodium removal ismuch poorer t aforesaid saturated ammonia resin. The resulting stableammonium silicate solution contained 0.11% of Na O, 2.02% of (NH O,5.73% of SiO and had mole ratios of SiO /Na O of 53.8 and SiO /(NH O of2.46.

This ammonium silicate solution was used as a deflocculating agent formixtures containing 20% of Barden clay. Barden clay is an air-separatedkaolin clay obtained from Huber Bros. Inc. A total of 320 grams of theammonium silicate solution diluted with water was prepared and Bardenclay added to the solution. The final mixture was agitated with aHamilton-Beach mixer for one minute and then allowed to stand for oneminute. The viscosity was then determined using a Brookfield viscometerwith the No. 3 spindle used at 50 rpm. for thirty seconds. The followingtable of results shows that our ammonium silicate is an effectivedeflocculating agent for clay:

Silicate Silicate Viscosity Clay, g. H2O, g. Soln. g. Solids, g.Brookfield Value Example 8 The ammonium silicate of Example 7 was alsoused for the preparation of a cold setting water-resistant adhesive. Acold setting adhesive was prepared with 24.0 grams of Purina protein, anisolated soy protein sold by Ralston Purina Co., (8.0%), 44.0 grams ofParagon clay (14.65%), 132.0 grams of ammonium silicate (43.95%), 100grams of water (33.3%) and 0.25 gram of sodium sulfite (0.08%). Asmooth, uniform mixture was obtained having 2.52% of SiO After aging onehour it had a viscosity at 25 C. of 500 stormer seconds (plus 100grams). After five hours the viscosity was 230 seconds, after 26 hoursit was 224 seconds and after 71 hours it was 142 seconds. The mixturethinned out somewhat more on storage for 14 days but showed no sign ofspoilage.

This cold setting composition was used to bond corrugated specimens of Bflute single face Chemfiber medium and Wethe rtex liner, both obtainedfrom International Paper Co. Four specimens measuring 2 X 3 inches wereprepared and the samples aged for 3 days at 75 F. at 50% humidity. Theywere then cut into /2 inch strips for the determination of dry strength,/2 hour soaking strength and 24 hours soaking strength, and the strengthafter soaking for 24 hours and redrying for one week under standardconditions. Tensile strength is given in pounds per 12 inches of flutetip length. The dry strength was 29.2 lbs.; after 0.5 hour soaking andafter 24 hours soaking the strength was about 1.5 lbs.; and after 24hours soaking and redrying the strength was again 27.6 lbs. This is avery satisfactory performance.

Other samples of this bond were heat set by heating on a hot plate at360 F. for seconds. After aging as before, these samples had a drystrength of 41.6 lbs. and a redried strength after soaking for 24 hoursof 45.2 lbs.

More or less detailed claims will be presented hereinafter and eventhough such claims are rather specific in nature, those skilled in theart to which this invention pertains will recognize that there areobvious equivalents for the specific materials recited therein. Some ofthese obvious equivalents are disclosed herein, other obviousequivalents will immediately occur to one skilled in the art and stillother obvious equivalents could be readily ascertained upon rathersimple, routine, non-inventive experimentation. Certainly no inventionwould be involved in substituting one or more of such obviousequivalents for the materials specifically recited in the claims. Forexample, other selective means such as permselective membranes andelectrolytic processes are quite possibly applicable to the presentinvention. It is intended that all such obvious equivalents beencompassed within the scope of this invention and patent grant inaccordance with the well-known doctrine of equivalents, as well aschanged proportions of the ingredients which do not render thecomposition unsuitable for the disclosed purposes.

What is claimed is:

1. The method which comprises:

(a) introducing an aqueous solution of an alkali metal silicate into areaction zone,

(b) also introducing into said reaction zone a material selected fromthe group consisting of ammonia and ammonium hydroxide and bringing saidmater1al into admixture with said alkali metal silicate to therebyproduce a double silicate solution of an alkali metal and ammonia, saiddouble silicate contaming from 1 to 12% SiO and having a ratio of from 2to 6 SiO /(NH O, 2 to 4 SiO /Na O and 0.4 to 2.5 (NH O/Na O,

(c) contacting said double silicate solution with a cation exchangeresin that is between about and saturated with ammonia;

(d1)1 recovering an ammonium silicate solution that (l) a ratio of Si0least 25; and (2) a ratio of (NH O to alkali metal oxide of at least 8;and (3) an average silica micelle size that does not exceed about 3millimicrons in diameter.

2. A method according to claim 1 wherein said alkali metal silicate issodium silicate.

3. The process of claim 2 in which the cation exchange resin III ahighly cross-linked nuclear sulfonic acid.

4. The process of claim 2 in which the ratio of solutron of doublesilicate to resin in the step of treating the double silicate is from0.45 to 2.5 gr./ml. and the contact time is greater than about 4minutes.

5. An ammonium silicate solution with silica micelles less than 5millimicrons in diameter and containing from 1 to 12% SiO a SiO toalkali metal oxide ratio of between about 25 and a (NH O to alkali metaloxide ratio of between about 8 and 40; and a ratio of S10 to (NH O ofbetween about 2 and 8.

l 6. The ammonium silicate solution of claim 5 containmg a watermiscible organic solvent.

to alkali metal oxide of at References Cited UNITED STATES PATENTS Re.25,252 10/1962 Reuter et al. 252313 2,978,419 4/1961 Birkhimer 2523133,012,050 12/1961 Fox et al. 23-110 X FOREIGN PATENTS 66,783 9/1957France.

OSCAR R. VERTIZ, Primary Examiner. A. I. GREIF, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION October 10, 1967Patent No. 3,346,334

Helmut Hans Wilhelm Weldes et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, line 21, for "remve" read remove line 41, for porduct" readproduct, line 51, for "slurred" read slurried same column 2, line 68,for "loading" read loadings column 3, line 5, for "reasonable" readreasonably line 28, after "alkali" insert metal line 31, for "sadium"read sodium line 37, for "longer' read larger line 49, for "(CNH O" read(NH O column 4, line 28, for "solid" read sold columns 5 and 6, in thesecond table, seventh column, line 6 thereof, for "5.87" read 5.83 sametable, seventh column, line 8 thereof, for "5.03" read 5,70 column 6,line 1, before "about" insert to same column 6, lines 58, 70, 2, and 74,and column 7, lines 24, 33, 34, 37, and 40, for "D", each occurrence,read "D" column .8, line 75, for "wtih" read with column 9, line 50, for'Wethertex" read Weathertex Signed and sealed this 24th day of December1968.

(SEAL) Attest:

EDWARD J. BRENNER EDWARD M.FLETCHER,JR.

Commissioner of Patents Attesting Officer

1. THE METHOD WHICH COMPRISES: (A) INTRODUCING AN AQUEOUS SOLUTION OF ANALKALI METAL SILICATE INTO A REACTION ZONE, (B) ALSO INTRODUCING INTOSAID REACTION ZONE A MATERIAL SELECTED FROM THE GROUP CONSISTING OFAMMONIA AND AMMONIUM HYDROXIDE AND BRINGING SAID MATERIAL INTO ADMIXTUREWITH SAID ALKALI METAL SILICATE TO THEREBY PRODUCE A DOUBLE SILICATESOLUTION OF AN ALKALI METAL AND AMMONIA, SAID DOUBLE SILICATE CONTAININGFROM 1 TO 12% SIO2 AND HAVING A RATIO OF FROM 2 TO 6 SIO2/(NH4)2O, 2 TO4 SIO2/NA2O AND 0.4 TO 2.5 (NH4)2O/NA2O, (C) CONTACTING SAID DOUBLESILICATE SOLUTION WITH A CATION EXCHANGE RESIN THAT IS BETWEEN ABOUT 75AND 100% SATURATED WITH AMMONIA; (D) RECOVERING AN AMMONIUM SILICATESOLUTION THAT HAS: (1) A RATIO OF SIO2 TO ALKALI METAL OXIDE OF AT LEAST25; AND (2) A RATIO OF (NH4)2O TO ALKALI METAL OXIDE OF AT LEAST 8; AND(3) AN AVERAGE SILICA MICELLE SIZE THAT DOES NOT EXCEED ABOUT 3MILLIMICRONS IN DIAMETER.